1. Field of the Invention
The present invention relates to an organic thin film transistor (OTFT) and a method of fabricating the same, and more particularly, to an OTFT and a method of fabricating the same in which an organic layer and metal interconnections thereof are formed to have certain linewidths and shapes.
2. Description of the Related Art
In general, a thin film transistor (TFT) includes a semiconductor layer, a gate electrode, and source and drain electrodes. In more detail, the semiconductor layer includes heavily-doped source and drain regions and a channel region interposed between the source and drain regions. The gate electrode is electrically isolated from the semiconductor layer and disposed in a region corresponding to the channel region. Also, the source and drain electrodes are in contact with the source and drain regions, respectively. The TFT may function as a switching and/or a driving device for a flat panel display (FPD), such as a liquid crystal display (LCD) or an organic light emitting display (OLED), to control operations of one or more pixels of the FPD.
In at least some applications, it is required that FPDs be made to be thin and flexible. Thus, there have been many attempts at adopting a plastic substrate in place of a conventional glass substrate such that the FPDs are more flexible. In making use of the plastic substrate, a method of fabricating a TFT at a low temperature has been under study.
As a result, an organic TFT (OTFT) including an organic semiconductor layer has attracted much attention. The OTFT can embody a low-cost TFT because it may be fabricated at a low temperature. However, during fabrication of the OTFT, the organic semiconductor layer can be damaged by an organic solvent when the organic semiconductor layer is produced by using a photolithography process. Thus, device characteristics of the OTFT may be adversely affected.
Therefore, an inkjet printing method is often used in place of the photolithography process, to prevent device characteristics of the OTFT from being adversely affected and to simplify the fabrication process. In addition, the inkjet printing method neither requires use of an expensive deposition chamber nor consumes a large amount of materials.
However, the inkjet printing method requires surface processing to be performed in advance since, when ink is applied to a desired location, a linewidth and a shape of the applied ink are determined by surface properties of the desired location. The surface processing is often performed using a chemical etching technique and/or a plasma etching technique. Even when surface processing is performed, however, it is still difficult to use the inkjet printing method to produce an organic layer and metal interconnections having linewidths and shapes that are substantially uniform. As a result, interconnection resistances are increased, thereby adversely affecting device characteristics of the OTFT.